This interrupt, if enabled, will wake the microcontroller from SLEEP.. The PIC16CXXX is normally in SLEEP mode with the “change on state” interrupt enabled.. Since the PIC16CXXX is in SL
Trang 1INTRODUCTION
Microchip's PIC16CXXX microcontroller family are ide-ally suited to directly interface to a keypad The high 4-bits of PORTB (RB7:RB4) have internal pull-ups and can trigger a “change on state” interrupt This interrupt,
if enabled, will wake the microcontroller from SLEEP In most battery powered applications, a microcontroller is exercised when a key is pressed (e.g., in a remote key-less entry system) The life of the battery can be extended by using PIC16CXXX microcontrollers This
is done by putting the PIC16CXXX microcontroller into SLEEP mode for most of the time and wake-up only when a key is pressed
IMPLEMENTATION
Figure 1 depicts an application where four keys are connected to RB7:RB4 Internal pull-ups are used to maintain a high level on these inputs In this example, LEDs are connected to RB3:RB0 When SW1 is pressed, LED1 is turned on and when SW2 is pressed, LED2 is turned on and so on The PIC16CXXX is normally in SLEEP mode with the “change on state”
interrupt enabled When SW1 is pressed, RB4 goes low and triggers an interrupt Since the PIC16CXXX is in SLEEP, it first wakes up and starts executing code at the interrupt vector Note that if the global interrupt is enabled, the program execution after an interrupt is at the interrupt vector, if the global interrupt is not enabled, the program starts executing the first line of code right after the SLEEP instruction
After waking up, a 20 - 40 ms de-bounce delay is executed which checks the port for a key hit and, depending on which key is hit, its associated LED is turned on The LEDs are used purely for demonstration purposes In a remote keyless entry application, the remote code would be transmitted when the appropriate key is hit
Figure 2 depicts a 4x4 keypad interface to a PIC16CXXX microcontroller When using the PIC16CXXX in a keypad application, the internal pull-ups on RB7:RB4 can be enabled, eliminating the need for external pull-up resistors The series 100Ω resistors are used for Electrostatic Discharge (ESD) protection, and are recommended in keypad interface applications
Microchip Technology Inc
SUMMARY
The PIC16CXXX is ideally suited to interface directly to
a keypad application Built in pull-up resistors and very low current consumption during sleep make it a very good candidate for battery powered remote operations and applications Appendix A provides an example of the code
Performance:
FIGURE 1: 4 KEY INTERFACE TO
PIC16CXXX
FIGURE 2: 4x4 KEYPAD INTERFACE TO
PIC16CXXX
LED1 LED2 LED3 LED4
SW1 SW2 SW3 SW4
RB0 RB1 RB2 RB3 RB4 RB5 RB6 RB7
PIC16CXXX 4x100Ω
4x1k
RB0 RB1 RB2 RB3 RB4 RB5 RB6 RB7
PIC16CXXX
8x100Ω
4x4 Key Matrix
AN552
Implementing Wake-up on Key Stroke
Trang 2APPENDIX A : WAKUP.ASM
MPASM 01.40 Released WAKUP.ASM 1-16-1997 16:04:19 PAGE 1
LOC OBJECT CODE LINE SOURCE TEXT
VALUE
00001 ;This program demonstrates the wake-up on Keystroke feature of
00002 ;the PIC16C71 Port B pins RB4 - RB7 can be configured as inputs with
00003 ;internal pull up resistors, also the interrupt associated with the
00004 ;change on input on RB4 - RB7 can be set up to wake the chip from
00005 ;sleep If the global interrupt is enabled just before sleep, the
00006 ;program will vector to the interrupt vector (0004) If not, the chip
00007 ;will continue execution just after the next instruction following
00008 ;sleep In this example code, port B is initialized to input 4
00009 ;push-buttons at RB4 - RB7 RB0 - RB3 are configured to drive LEDs
00010 ;corresponding to which pushbutton is hit (LED on RB0 when RB4 is
00011 ;hit and so on) Sleep is executed When any key is hit, the
00012 ;processor wakes up and jumps to the interrupt vector The
00013 ;corresponding LED is turned on and after the key is released, the
00014 ;whole process is repeated
00015 ;
00016 ; Program: WAKEUP.ASM
00017 ; Revision Date:
00018 ; 1-16-97 Compatibility with MPASMWIN 1.40
00019 ;
00020 ;************************************************************************
00021 ;
00022 LIST P=16C71
00023 ;
00000002 00024 z equ 2
00000007 00025 RBPU equ 7
00000010 00026 temp equ 10h
00000001 00027 OptionReg equ 1h
00000001 00028 F EQU 1
00029 ;
00030 include "p16c71.inc"
00001 LIST
00002 ;P16C71.INC Standard Header File, Version 1.00 Microchip Technology
00142 LIST
00031 ;
0000 00032 org 0
0000 2805 00033 goto start
00034 ;
0004 00035 org 4
0004 2808 00036 goto ServiceInterrupt
00037 ;
00038 ;
0005 00039 start
0005 2024 00040 call InitPortB ;initialize port B
0006 00041 loop
00042 sleep ;sleep till key is hit
0006 0000 00043 nop
0007 2806 00044 goto loop
00045 ;
0008 00046 ServiceInterrupt
0008 180B 00047 btfsc INTCON,RBIF ;change on rb int?
0009 280D 00048 goto ServiceWakup ;yes then service
000A 128B 00049 bcf INTCON,T0IE ;clear TMR0 int mask
000B 110B 00050 bcf INTCON,T0IF ;clear flag
000C 0008 00051 return
Please check the Microchip BBS for the latest version of the source code Microchip’s Worldwide Web Address: www.microchip.com; Bulletin Board Support: MCHIPBBS using CompuServe® (CompuServe membership not required)
Trang 300052 ;
00053 ;This routine checks which key is hit and lights up the
00054 ;corresponding LED associated with it eg RB0's LED when
00055 ;RB4's key is pressed Finally it waits till all keys have
00056 ;been released before returning form the service routine
000D 00057 ServiceWakup
000D 118B 00058 bcf INTCON,RBIE ;clear mask
000E 0906 00059 comf PORTB,W ;read PORTB
000F 100B 00060 bcf INTCON,RBIF ;clear flag
0010 2035 00061 call delay16 ;do de-bounce for 16mSecs
0011 0906 00062 comf PORTB,W ;read port B again
0012 39F0 00063 andlw B'11110000' ;mask outputs
0013 0090 00064 movwf temp ;save in temp
0014 0E10 00065 swapf temp,W ;switch low and high
0015 0086 00066 movwf PORTB ;send as outputs
0016 2018 00067 call KeyRelease ;check for key release
0017 0009 00068 retfie
00069 ;
00070 ;This sub-routine, waits till all key have been released
00071 ;In order to save power, the chip is in sleep mode till
00072 ;all keys are released
0018 00073 KeyRelease
0018 2035 00074 call delay16 ;do debounce
0019 0906 00075 comf PORTB,W ;read PORTB
001A 100B 00076 bcf INTCON,RBIF ;clear flag
001B 158B 00077 bsf INTCON,RBIE ;enable mask
001C 39F0 00078 andlw B'11110000' ;clear outputs
001D 1903 00079 btfsc STATUS,z ;key still pressed?
001E 0008 00080 return ;no then return
001F 0063 00081 sleep ;else save power
0020 118B 00082 bcf INTCON,RBIE ;on wake up clear mask
0021 0906 00083 comf PORTB,W
0022 100B 00084 bcf INTCON,RBIF ;clear flag
0023 2818 00085 goto KeyRelease ;try again
00086 ;
00087 ;
00088 ;This sub-routine, initializes PortB
0024 00089 InitPortB
0024 1683 00090 bsf STATUS,RP0 ;select bank1
0025 3003 00091 movlw B'00000011' ;Port_A digital I/O
Message[302]: Register in operand not in bank 0 Ensure that bank bits are correct
0026 0088 00092 movwf ADCON1 ; /
0027 3000 00093 movlw 0 ;
0028 0085 00094 movwf PORTA ;set port a as outputs
0029 30F0 00095 movlw B'11110000' ;RB0-RB3 outputs
002A 0086 00096 movwf PORTB ;RB4-RB7 inputs
002B 1381 00097 bcf OptionReg,RBPU ;enable pull up
002C 1283 00098 bcf STATUS,RP0 ;select page 0
002D 0186 00099 clrf PORTB ;init port B
002E 0185 00100 clrf PORTA ;make port a all low
002F 1405 00101 bsf PORTA,0 ;make first bit high
0030 118B 00102 bcf INTCON,RBIE ;disable mask
0031 0806 00103 movf PORTB,W ;read port
0032 100B 00104 bcf INTCON,RBIF ;clear flag
0033 158B 00105 bsf INTCON,RBIE ;enable mask
0034 0009 00106 retfie ;enable global and return
00107 ;
00108 ;delay16 waits for approx 16.4mSecs using TMR0 interrupts
00109 ;fosc speed is 4Mhz
0035 00110 delay16
0035 1683 00111 bsf STATUS,RP0 ;select Bank1
0036 3007 00112 movlw B'00000111' ;fosc/256 > TMR0
0037 0081 00113 movwf OptionReg ; /
0038 1283 00114 bcf STATUS,RP0 ;select Bank0
0039 0181 00115 clrf TMR0
003A 110B 00116 bcf INTCON,T0IF ;clear flag
Trang 4003B 168B 00117 bsf INTCON,T0IE ;enable mask
003C 00118 CheckAgain
003C 1D0B 00119 btfss INTCON,T0IF ;timer overflowed?
003D 283C 00120 goto CheckAgain ;no check again
003E 128B 00121 bcf INTCON,T0IE ;else clear mask
003F 110B 00122 bcf INTCON,T0IF ;clear flag
0040 0008 00123 return
00124 ;
00125 end
MEMORY USAGE MAP ('X' = Used, '-' = Unused)
0000 : X -XXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX
0040 : X -
-All other memory blocks unused
Program Memory Words Used: 62
Program Memory Words Free: 962
Errors : 0
Warnings : 0 reported, 0 suppressed
Messages : 1 reported, 0 suppressed
Trang 5Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates It is your responsibility to
ensure that your application meets with your specifications
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise Use of Microchip’s products as critical
com-ponents in life support systems is not authorized except with
express written approval by Microchip No licenses are
con-veyed, implicitly or otherwise, under any intellectual property
rights
Trademarks
The Microchip name and logo, the Microchip logo, FilterLab,
KEELOQ, microID, MPLAB, PIC, PICmicro, PICMASTER, PICSTART, PRO MATE, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Tech-nology Incorporated in the U.S.A and other countries
dsPIC, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, microPort, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, MXDEV, PICC, PICDEM, PICDEM.net, rfPIC, Select Mode and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A
Serialized Quick Turn Programming (SQTP) is a service mark
of Microchip Technology Incorporated in the U.S.A
All other trademarks mentioned herein are property of their respective companies
© 2002, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved
Printed on recycled paper.
Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999 The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro ® 8-bit MCUs, K EE L OQ ® code hopping devices, Serial EEPROMs and microperipheral products In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified.
The person doing so may be engaged in theft of intellectual property
• Microchip is willing to work with the customer who is concerned about the integrity of their code
• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code Code protection does not mean that we are guaranteeing the product as “unbreakable”
• Code protection is constantly evolving We at Microchip are committed to continuously improving the code protection features of our product
If you have any further questions about this matter, please contact the local sales office nearest to you
Trang 6 2002 Microchip Technology Inc.
M
AMERICAS
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200 Fax: 480-792-7277
Technical Support: 480-792-7627
Web Address: http://www.microchip.com
Rocky Mountain
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7966 Fax: 480-792-7456
Atlanta
500 Sugar Mill Road, Suite 200B
Atlanta, GA 30350
Tel: 770-640-0034 Fax: 770-640-0307
Boston
2 Lan Drive, Suite 120
Westford, MA 01886
Tel: 978-692-3848 Fax: 978-692-3821
Chicago
333 Pierce Road, Suite 180
Itasca, IL 60143
Tel: 630-285-0071 Fax: 630-285-0075
Dallas
4570 Westgrove Drive, Suite 160
Addison, TX 75001
Tel: 972-818-7423 Fax: 972-818-2924
Detroit
Tri-Atria Office Building
32255 Northwestern Highway, Suite 190
Farmington Hills, MI 48334
Tel: 248-538-2250 Fax: 248-538-2260
Kokomo
2767 S Albright Road
Kokomo, Indiana 46902
Tel: 765-864-8360 Fax: 765-864-8387
Los Angeles
18201 Von Karman, Suite 1090
Irvine, CA 92612
Tel: 949-263-1888 Fax: 949-263-1338
New York
150 Motor Parkway, Suite 202
Hauppauge, NY 11788
Tel: 631-273-5305 Fax: 631-273-5335
San Jose
Microchip Technology Inc.
2107 North First Street, Suite 590
San Jose, CA 95131
Tel: 408-436-7950 Fax: 408-436-7955
Toronto
6285 Northam Drive, Suite 108
Mississauga, Ontario L4V 1X5, Canada
Tel: 905-673-0699 Fax: 905-673-6509
ASIA/PACIFIC
Australia
Microchip Technology Australia Pty Ltd Suite 22, 41 Rawson Street
Epping 2121, NSW Australia Tel: 61-2-9868-6733 Fax: 61-2-9868-6755
China - Beijing
Microchip Technology Consulting (Shanghai) Co., Ltd., Beijing Liaison Office
Unit 915 Bei Hai Wan Tai Bldg.
No 6 Chaoyangmen Beidajie Beijing, 100027, No China Tel: 86-10-85282100 Fax: 86-10-85282104
China - Chengdu
Microchip Technology Consulting (Shanghai) Co., Ltd., Chengdu Liaison Office
Rm 2401, 24th Floor, Ming Xing Financial Tower
No 88 TIDU Street Chengdu 610016, China Tel: 86-28-6766200 Fax: 86-28-6766599
China - Fuzhou
Microchip Technology Consulting (Shanghai) Co., Ltd., Fuzhou Liaison Office
Unit 28F, World Trade Plaza
No 71 Wusi Road Fuzhou 350001, China Tel: 86-591-7503506 Fax: 86-591-7503521
China - Shanghai
Microchip Technology Consulting (Shanghai) Co., Ltd.
Room 701, Bldg B Far East International Plaza
No 317 Xian Xia Road Shanghai, 200051 Tel: 86-21-6275-5700 Fax: 86-21-6275-5060
China - Shenzhen
Microchip Technology Consulting (Shanghai) Co., Ltd., Shenzhen Liaison Office
Rm 1315, 13/F, Shenzhen Kerry Centre, Renminnan Lu
Shenzhen 518001, China Tel: 86-755-2350361 Fax: 86-755-2366086
Hong Kong
Microchip Technology Hongkong Ltd.
Unit 901-6, Tower 2, Metroplaza
223 Hing Fong Road Kwai Fong, N.T., Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431
India
Microchip Technology Inc.
India Liaison Office Divyasree Chambers
1 Floor, Wing A (A3/A4)
No 11, O’Shaugnessey Road Bangalore, 560 025, India Tel: 91-80-2290061 Fax: 91-80-2290062
Japan
Microchip Technology Japan K.K.
Benex S-1 6F 3-18-20, Shinyokohama Kohoku-Ku, Yokohama-shi Kanagawa, 222-0033, Japan Tel: 81-45-471- 6166 Fax: 81-45-471-6122
Korea
Microchip Technology Korea 168-1, Youngbo Bldg 3 Floor Samsung-Dong, Kangnam-Ku Seoul, Korea 135-882 Tel: 82-2-554-7200 Fax: 82-2-558-5934
Singapore
Microchip Technology Singapore Pte Ltd.
200 Middle Road
#07-02 Prime Centre Singapore, 188980 Tel: 65-334-8870 Fax: 65-334-8850
Taiwan
Microchip Technology Taiwan 11F-3, No 207
Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
EUROPE
Denmark
Microchip Technology Nordic ApS Regus Business Centre Lautrup hoj 1-3 Ballerup DK-2750 Denmark Tel: 45 4420 9895 Fax: 45 4420 9910
France
Microchip Technology SARL Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu Batiment A - ler Etage
91300 Massy, France Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79
Germany
Microchip Technology GmbH Gustav-Heinemann Ring 125 D-81739 Munich, Germany Tel: 49-89-627-144 0 Fax: 49-89-627-144-44
Italy
Microchip Technology SRL Centro Direzionale Colleoni Palazzo Taurus 1 V Le Colleoni 1
20041 Agrate Brianza Milan, Italy Tel: 39-039-65791-1 Fax: 39-039-6899883
United Kingdom
Arizona Microchip Technology Ltd.
505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44 118 921 5869 Fax: 44-118 921-5820
01/18/02
W ORLDWIDE S ALES AND S ERVICE